Flexible goggles having a flexible housing in which a lens is mounted are well-known. Such goggles often use a thermal lens which includes two lenses spaced in parallel relation, such as by a closed cell foam spacer, to form an air-tight chamber between the two lenses for providing thermal insulation. Such goggles are commonly used by skiers and motorcyclists to protect their eyes from wind, precipitation and debris. They may also be used by surgeons and other medical personnel during operations and the like to protect eyes from fluids such as blood. The major drawback of conventional goggles is that condensation has a tendency to form on the inside of the lens thus fogging the lens and blocking the user's vision.
To prevent fogging, ski goggles have been provided with ventilating apertures which overcome the drawback of fogging, but which may, under some circumstances, allow excessive ventilation. This excessive ventilation results in a stream of cold air which may be unpleasant to the user, especially in extremely cold weather. Moreover, excessive ventilation can dry or otherwise damage sensitive tissue in and around the eyes. It has been proposed to control the passage of air by pivotable automatic flaps for closing an air passage opening when the user reaches a certain minimum speed. However, such devices are not practical, can be subject to icing of the closure mechanism, and are not manually adjustable by the user.
Ideally, a ventilation system for flexible goggles would be inexpensive to manufacture, manually adjustable and easy to operate. Ease of use is particularly important because users may often be wearing gloves or mittens which reduce their dexterity.